In my opinion, the best way is to call someone who has done it before. You don't mention the problems you're experiencing. Could the solution to your issues be something as simple as cleaning out under the traveling magnets, or do the problems you're experiencing point at worn guide castings.
As already stated above, leave it to someone who has done it before especially if you have a preset plus feeder. Preset feeders are a bit easier in some ways but usually a good cleaning will be good enough unless the lever is dished out and the bearing is worn.
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